Attosecond time delays in heavy-ion induced fission measured by crystal blocking

作者：Andersen J U^*; Chevallier J; Forster J S; Karamian S A; Vane C R; Beene J R; Galindo Uribarri A; del Campo J Gomez; Gross C J; Krause H F; Padilla Rodal E; Radford D; Shapira D; Broude C; Malaguti F; Uguzzoni A

来源：Physical Review C, 2008, 78(6): 064609.

DOI：10.1103/PhysRevC.78.064609

The time delays in fission induced by bombardment of W with 180 MeV (32)S, 240-255 MeV (48)Ti, 330-375 MeV (58)Ni, and 390 MeV (74)Ge have been measured by observation of crystal blocking. Nearly all results are consistent with exponential decay with lifetimes of order 10(-18) s which depend weakly on the atomic number of the composite nucleus. This is inconsistent with the Bohr-Wheeler model of fission from a compound nucleus in statistical equilibrium at each stage in a neutron evaporation cascade and supports a picture of strongly damped quasifission. A simple diffusion model with one-body dissipation reproduces roughly the observed time scale and the exponential decay. It suggests that the outer fission barrier could play a significant role in the observed, very slow decays.

• 出版日期2008-12